The focus of the program project is on the behavioral and biomedical correlates of the clinical course of defined groups of individuals with (senile) demential of the Alzheimer type (SDAT/DAT) in comparison with the course of healthy aging. The psychometric core contributes to this effort by administering a battery of psychometric tests that assess memory (primary, secondary, semantic) as well as visuospatial and visuoconstructive, speeded psychomotor, sensory/motor, and language abilities. They are used to document the cognitive status of the research participants. These measures will also be related to clinical and neurapathological indices to determine the behavioral- neuropathological correlates in SDAT among the very old. They will also provide information about psychometric test performance in very late life in individuals who are not clinically demented. Psychometric test performance will be compared with data obtained from laboratory studies of memory processes to address the theoretical mechanisms underlying cognitive deficits in SDAT/DAT, especially very early in the course of the disease. Longitudinal changes in psychometric test performance will be compared with changes in hormone/metabolite changes, again in an effort to understand the mechanisms of the disease.